Merge pull request #2 from adenexter/master

[qtdocgallery] Translate orientation strings to integer values.
Merge pull request #3 from adenexter/master

[qtdocgallery] Support the orientation value for all file types.
[qtdocgallery] Expose properties common to multiple type through File.
[qtdocgallery] Search for videos using the nmm:Video type instead of nfo:Video

GraphUpdated notifications aren't emitted with the nfo:Video type so
updates are missed.